It is known to apply bismaleimides and maleimide-amide compounds as bifunctional monomer or comonomer in compositions that are cured thermally by an addition reaction or via radicals. EP-A-136964 discloses a composition comprising bismaleimide and maleimide-amide compounds. The polymers and objects prepared thereof have excellent properties, such as a high HDT (heat distortion temperature) and a good resistance to hydrolysis.
A disadvantage of the products prepared on the basis of those compositions is their brittleness or low impact strength, as is apparent from, for instance, the low percentage of the elongation at break (from a tensile test). A general method for reducing the brittleness is to incorporate thermoplastics, rubbers or elastomers in the composition. To obtain a good impact strength of the fully cured polymer, it is desirable for the rubber to form a fine, properly dispersed microphase in the polymer matrix.
The bismaleimide and maleimide-amide compounds mentioned in EP-A-135964 can be polymerized both with and without comonomer. As comonomer, use can be made of a vinyl aromatic compound such as styrene. If this comonomer is used, thermoplastics, rubbers or elastomers cannot be dissolved in the mixtures containing bismaleimide and maleimide-amide without further measures being taken.